chore(deps): update documentation dependencies

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
furo	==2024.7.18 -> ==2024.8.6
sphinx-design	==0.6.0 -> ==0.6.1
sphinx-notfound-page	==1.0.2 -> ==1.0.4

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Release Notes

pradyunsg/furo (furo)

### [`v2024.8.6`](https://togithub.com/pradyunsg/furo/compare/2024.07.18...2024.08.06) [Compare Source](https://togithub.com/pradyunsg/furo/compare/2024.07.18...2024.08.06)

executablebooks/sphinx-design (sphinx-design)

### [`v0.6.1`](https://togithub.com/executablebooks/sphinx-design/blob/HEAD/CHANGELOG.md#061---2024-08-02) [Compare Source](https://togithub.com/executablebooks/sphinx-design/compare/v0.6.0...v0.6.1) - ⬆️ Update sphinx to >=6,<9 by {user}`chrisjsewell` in {pr}`212` - 👌 Reduce right-padding of dropdown title by {user}`chrisjsewell` in {pr}`198`

readthedocs/sphinx-notfound-page (sphinx-notfound-page)

### [`v1.0.4`](https://togithub.com/readthedocs/sphinx-notfound-page/blob/HEAD/CHANGELOG.rst#Version-104) [Compare Source](https://togithub.com/readthedocs/sphinx-notfound-page/compare/1.0.3...1.0.4) :Date: Jul 31, 2024 - Fix issue when installing with Sphinx 7.2.x and `notfound_urls_prefix=None` ### [`v1.0.3`](https://togithub.com/readthedocs/sphinx-notfound-page/blob/HEAD/CHANGELOG.rst#Version-103) [Compare Source](https://togithub.com/readthedocs/sphinx-notfound-page/compare/1.0.2...1.0.3) :Date: Jul 30, 2024 - Fix `_Opt` deprecation warning

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